(a) Technical Field
The present disclosure relates to an apparatus and method for manufacturing a fuel cell membrane-electrode assembly (MEA). More particularly, it relates to an apparatus and method for manufacturing a fuel cell membrane-electrode assembly by forming a catalyst layer, which has uniform distribution, excellent porosity, and excellent bondability to a polymer electrolyte membrane, on a metal roll by an electrospray process and transferring the catalyst layer to a polymer electrolyte membrane.
(b) Background Art
A fuel cell stack, which substantially generates electricity, in a fuel cell system has a structure in which several tens to several hundreds of unit cells, each comprising a membrane-electrode assembly (MEA) and a separator, are stacked together.
The MEA comprises a polymer electrolyte membrane, a negative electrode and a positive electrode, which are disposed on each of both sides of the polymer electrolyte membrane. The negative electrode (“hydrogen electrode”, “fuel electrode”, “anode”, or “oxidizing electrode”) and the positive electrode (“air electrode”, “oxygen electrode”, “cathode”, or “reducing electrode”) are configured in such a manner that a catalyst layer comprising platinum catalyst nanoparticles is formed on an electrode backing layer such as carbon paper or carbon cloth.
Conventional methods for manufacturing membrane-electrode assemblies will be described below. As shown in FIG. 3, a catalyst slurry is coated, sprayed or painted on a gas diffusion layer to form an electrode, and the electrode is bonded to a polymer electrolyte membrane by thermal compression. Otherwise, as shown in FIG. 4, a catalyst slurry is coated, sprayed or painted directly on a polymer membrane and the resulting polymer membrane is bonded to a gas diffusion layer. As another method, as shown in FIG. 5, a catalyst slurry is coated, sprayed or painted on a release paper and transferred to a polymer membrane to form an electrode, and the electrode is bonded to a gas diffusion layer.
However, when the catalyst slurry is applied on the gas diffusion layer as in FIG. 3, it is advantageous to form pores but is inconvenient to manufacture the MEA, and thus it is not used in a commercial process.
Moreover, the method of directly forming the catalyst layer on the polymer membrane as in FIG. 4 can manufacture small area electrodes. However, during manufacturing of large area electrodes, when the catalyst layer is in contact with the polymer membrane, the polymer membrane absorbs the catalyst slurry and is deformed. Therefore, it is difficult to manufacture the large area electrode due to the deformation of the polymer membrane.
Furthermore, in the case of the method of forming the catalyst layer on the release paper and transferring the catalyst layer to the polymer membrane as in FIG. 5, a process of transferring the catalyst layer to the polymer membrane by compression at high temperature and pressure is required after forming the catalyst layer on the release paper. Moreover, the bonding between the catalyst layer and the polymer membrane is incomplete, which causes deterioration of performance and durability.
The method of forming the catalyst layer generally includes a method of spraying a catalyst slurry on a substrate (e.g., membrane, release paper, gas diffusion layer, etc) using a spray and a method of coating a liquefied catalyst slurry on a substrate using a coater.
In the case of forming the catalyst layer by the spray method, pores are formed in the catalyst layer, and thus the supply of fuel and the discharge of produced water are facilitated. However, the amount of catalyst lost is large, it takes a long time to form the catalyst layer, and materials (e.g., catalyst, binder, other additives, etc.) mixed with the catalyst slurry are non-uniformly formed in the catalyst layer.
Moreover, in the case of coating a liquefied catalyst slurry on the substrate, the amount of catalyst lost is small and it takes a short time to form the catalyst layer. However, materials (e.g., catalyst, binder, other additives, etc.) mixed with the catalyst slurry are non-uniformly formed in the catalyst layer, and the catalyst layer is densely formed, which prevents the formation of pores and makes it difficult to supply fuel and discharge produced water.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.